Alopecia areata is not like some genetic diseases in which a child has a 50-50 chance of developing the disease if one parent has it. Scientists believe that there may be a number of genes that predispose certain people to the disease. It is highly unlikely that a child would inherit all of the genes needed to predispose him or her to the disease.

Even with the right (or wrong) combination of genes, alopecia areata is not a certainty. In identical twins, who share all of the same genes, the concordance rate is only 55 percent. In other words, if one twin has the disease, there is only a 55 percent chance that the other twin will have it as well. This shows that other factors besides genetics are required to trigger the disease.